This invention relates generally to rotary regenerative heat exchangers employed in gas turbine engines and in particular to rubbing seal structures for applying to such heat exchangers.
Since such a sealing device is exposed to extremely high temperatures, it is a usual practice that the seal is formed from a heat-refractory material such as nickel oxide coating on a suitable metal base plate. The coating of such material is formed on the entire surface area rubbing against the rotary regenerator. Consequently, nickel oxide worn off in a finely particled state is emitted to the engine exhaust gases passing through the regenerator outlet passage. This will very likely cause a health hazard as gas turbine engines tend to be more and more widely employed.